In general terms, this invention relates to shock absorbers for vehicle suspensions. More particularly, this invention relates to a shock absorber that has adjustable damping based upon vehicle load.
Vehicle suspensions typically include shock absorbers for accommodating the variations in road surfaces that are encountered by a vehicle. The shock absorbers provide a more comfortable or consistent ride to the vehicle.
Many larger vehicles, such as trucks, also include air springs that have a chamber or bellows that is pressurized to provide an air cushion for the vehicle ride. While various combinations of shock absorber and air spring arrangements have been proposed, there is a need for improved ride control.
Various attempts have been made at providing variable suspension response by modifying the performance of shock absorbers or air springs depending on vehicle or road conditions. One shortcoming associated with many attempts is that additional components are added to provide additional functionality to the shock absorbers or air springs, for example. Such additional components introduce additional cost and complexity to the vehicle suspension. Moreover, vehicle packaging limitations render it difficult to add components onto existing structures.
For example, adjustable shock absorber assemblies have been proposed that include a separate chamber added onto a conventional shock absorber arrangement. The additional chamber then is coupled with a separate pressure source, such as an air source on the vehicle. The additional chamber renders it more difficult to place the shock absorber in a conventional position on a vehicle suspension. Additionally, there are further maintenance and other cost issues associated with such additional chambers.
There is a need for a shock absorber assembly that provides variable damping responsive to changes in the vehicle condition such as the amount of load on the vehicle. This invention provides a vehicle suspension with the ability to adapt to vehicle load conditions to provide variable damping or stiffness to ensure a more desirable or consistent ride while avoiding the shortcomings and drawbacks of prior attempts.
In general terms, this invention is a vehicle suspension assembly having a shock absorber with adjustable damping that changes responsive to changes in the vehicle load.
A vehicle suspension assembly designed according to this invention includes at least one air spring that is pressurized with air. At least one shock absorber has a central rod that moves in response to changing road conditions. The central rod includes a central bore that is coupled with the air supply to the air spring. Changes in pressure within the air spring result in changes in the damping level provided by the shock absorber.
In one example, a plunger is supported within the central bore of the rod and biased into a first position to provide a first damping condition. As air spring pressure increases, the plunger within the central bore is moved into a second position where increased shock absorber damping is provided. Because the pressure in the air spring increases with vehicle load, the shock absorber responsively provides increased damping. Therefore, a stiffer ride is provided under heavier vehicle load conditions, which results in a more consistent and desirable ride.
A significant advantage of this invention is that it allows for conventional shock absorber components to be used and does not require the addition of separate chambers or other complicated items to be added to a shock absorber. Additionally, this invention provides automatic damping adjustment responsive to the vehicle load.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.